PRP may help some people with knee osteoarthritis get less pain and better daily function over several months, but results depend on the PRP preparation and the knee problem being treated. The strongest recent summaries found better pain and function scores than placebo or some other injections, with benefits often most noticeable from about 3 to 12 months.
PRP means platelet-rich plasma: a clinician takes your blood, concentrates platelets, and injects that preparation into the knee. Platelets are blood cells involved in clotting and carry signaling proteins. If your knee pain comes from osteoarthritis, the National Institute of Arthritis and Musculoskeletal and Skin Diseases explains that cartilage and other joint tissues change over time; pain, stiffness, swelling, and reduced motion can follow.
Is PRP for the knee worth it?
It can be worth discussing if you want to compare injection options for knee osteoarthritis and understand the likely time frame. A 2025 meta-analysis in The American Journal of Sports Medicine combined 18 randomized controlled trials with 1,995 people with knee osteoarthritis. A randomized controlled trial is a study that assigns people to different treatments by chance. Compared with placebo injections, PRP improved pain and function scores; the pain difference met the study’s threshold for a meaningful change at 3 and 6 months.
That review also found an important practical detail: higher-platelet PRP had more durable results than lower-platelet PRP. This is why two clinics can both call an injection “PRP” while offering preparations that are not identical. Ask what preparation is planned and why it fits your knee findings.
An earlier 2021 meta-analysis of 34 randomized trials compared PRP with placebo and other injections in 2,829 knees. It found clinically meaningful advantages for some pain and function outcomes at 6 to 12 months, while also rating the overall quality of evidence as low. You can use the site’s guide to read a regenerative medicine study to see why study design, comparison group, and follow-up matter.
How long can PRP last in your knee?
The best available comparison studies commonly measured outcomes through 12 months. In the 2025 review, high-platelet PRP retained clinically meaningful function improvement through 12 months. In a 2021 randomized trial of 200 people with mild to moderate knee osteoarthritis, PRP was given as two injections three weeks apart; pain, stiffness, and function scores remained better at 12 months for the PRP group than for the hyaluronic-acid and ozone groups.
That does not make 12 months a promise for any one knee. It gives you a useful question for the appointment: what result would count as worthwhile for you, and when will you review whether it happened?
Is PRP better than a cortisone shot for knee pain?
The answer depends on the time frame and your reason for considering an injection. A 2023 systematic review and network meta-analysis in BMC Musculoskeletal Disorders compared corticosteroids, hyaluronic acid, PRP, and PRP plus hyaluronic acid across 35 studies involving 3,104 participants with knee osteoarthritis. PRP ranked best for the WOMAC score, a questionnaire covering pain, stiffness, and physical function, at 3 and 12 months. PRP plus hyaluronic acid ranked highest for some pain scores at 3 and 6 months.
| Option compared in the research | What the studies measured | What may matter to you |
|---|---|---|
| PRP | Pain and function scores at 3, 6, and 12 months | Results may vary with platelet concentration and protocol. |
| Corticosteroid | Pain and function scores in comparative trials | The network review ranked PRP higher for several longer follow-up outcomes. |
| Hyaluronic acid | Pain, stiffness, and function scores | PRP showed stronger results than hyaluronic acid in several later follow-ups. |
The studies do not turn one option into the right choice for everyone. Your clinician can relate the research to the source of your pain, imaging, activity goals, and prior treatment history.
What are the downsides of PRP injections?
The main downside is that the outcome is not uniform. PRP preparations, injection schedules, and study participants differ. The 2025 review found that lower-platelet PRP did not produce a clinically noticeable pain benefit in its platelet-concentration analysis, while higher-platelet PRP did.
For safety, the 2023 network meta-analysis recorded treatment-related adverse events and found no increase for PRP, corticosteroids, hyaluronic acid, or combination therapy compared with placebo. That is useful reassurance, but it is still worth asking about the clinic’s plan for pain or swelling after the injection and whom to contact if symptoms concern you. If you think a regenerative-medicine product or procedure has caused a problem, the site’s FDA side-effect reporting guide explains the reporting route.
Why might your knee hurt more after a PRP injection?
A short-term increase in pain is a question to raise before the procedure, because your own recovery plan should come from the clinician performing it. The comparative reviews tracked adverse events but do not give a single, reliable timeline for a post-injection pain flare. Ask what amount of soreness is expected in that clinic’s protocol, when to call, and how the team distinguishes an expected reaction from a problem that needs assessment.
Can PRP work if you are 50?
Age 50 by itself does not answer the question. Knee osteoarthritis becomes more common with age, but the NIAMS notes that symptoms and day-to-day impact vary widely from person to person. The randomized trial that compared PRP, hyaluronic acid, plasma rich in growth factors, and ozone had a mean participant age of 56.9 years, so people around 50 were represented in that research.
Ask how your cartilage changes, knee alignment, activity limits, and other health factors compare with the people studied. That conversation is more useful than an age cutoff.
Do you need PRP forever, or is something better?
The studies in this page followed people for months, not forever. A repeat injection is a planning question, not an automatic requirement. Ask the clinic what would lead them to suggest another injection, what measurement they will use to judge benefit, and what alternatives they would discuss if PRP does not meet your goal.
There is no single “better than PRP” option for every knee. For knee osteoarthritis, the National Center for Complementary and Integrative Health reports that tai chi improved pain, stiffness, balance, and physical function in research studies, and that an American College of Rheumatology/Arthritis Foundation guideline strongly recommends it for knee or hip osteoarthritis. The same NIH source says acupuncture is conditionally recommended for knee osteoarthritis, although the evidence remains controversial. These are options to put beside PRP in a clinician conversation, not replacements chosen from a webpage.
Should you wear a knee brace after PRP?
Ask the clinician who plans the injection whether a brace is part of your recovery plan and what it is meant to accomplish for your knee. The PRP trials summarized here measured pain, stiffness, and function; they do not establish one brace routine for every person after PRP.
Questions to bring to your PRP visit
- What is causing my knee pain, and does the PRP research apply to that problem?
- What PRP preparation and injection schedule do you use?
- What is the total cost, is it one injection or a series, and what does the price include?
- How will you measure whether it helped: pain, walking, stairs, sleep, or another goal?
- What should I expect in the first days after the injection, including pain, activity, and brace use?
- When should I contact the clinic about worsening pain or swelling?
- When will we reassess, and what are the next options if the result falls short?
For a fuller appointment checklist, see procedure conversation questions. If you are considering a research study instead of routine care, the guide to clinical trial records can help you understand the listing before you contact a research team.
By Regenerative Evidence Guide Editorial Team
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